U.S. Treasury Secretary Jacob Lew said on Wednesday that the government would run out of borrowing authority by late February if the Congress does not act to raise the debt limit before that time.

"When I previously wrote to you in December, I estimated that Treasury would exhaust extraordinary measures in late February or early March. Based on our best and most recent information, we believe that Treasury is more likely to exhaust those measures in late February," Lew said in a letter to the Congressional leaders including House Speaker John Boehner and Senate Majority Leader Harry Reid.

"While this forecast is subject to inherent variability, we do not foresee any reasonable scenario in which the extraordinary measures would last for an extended period of time," he added.

"I respectfully urge Congress to provide certainty and stability to the economy and financial markets by acting to raise the debt limit before Feb. 7, 2014, and certainly before late February," said Lew.

The U.S. Congress passed a two-year budget deal in December to avert the risk of a government shutdown. But the legislation didn't touch upon the issue of debt limit.

In October, the Congress agreed to suspend the federal government's borrowing limit until Feb. 7. If the debt ceiling isn't raised by then, Treasury will need to take measures to free up borrowing capacity in order to extend the debt limit for some time.

Lew explained that the length of time that the extraordinary measures can extend the country's borrowing authority is "significantly" shorter than in the past, partly because the government has to pay out large amounts of tax refunds in February.

The debt limit is the total amount of money that the federal government is authorized by the Congress to borrow to meet its existing legal obligations, including Social Security and Medicare benefits, military salaries, interest on the national debt, tax refunds, and other payments. Failing to increase the debt limit would cause the government to default on its legal obligations.

It is so far unclear how the both parties would address the debt limit, but some Republicans have hinted that they would demand concessions from Democrats to raise the debt ceiling.

Source: Xinhuanet